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The development of bioelectrochemical systems requires careful selection of both their biotic and abiotic components to obtain sustainable devices. Herein, we report a biophotoelectrode obtained with polyhydroxybutyrate (PHB), a biopolymer, which purple non-sulphur bacteria produce as an energy stock under specific environmental conditions. The electrode was obtained by casting a mixture composed of PHB and carbon fibers in a 3:2 mass ratio. Following, the composite material was modified with polydopamine and thermally treated to obtain a hydrophilic electrode with improved electrochemical behavior. The bio-based electrode was tested with metabolically active cells of Rhodobacter capsulatus embedded in a biohybrid matrix of polydopamine. The system achieved enhanced catalytic activity under illumination, with an 18-fold increase in photocurrent production compared to biophotoelectrodes based on glassy carbon, reaching a current density of 12 ± 3 μ A cm−2, after 30 min of light exposure at +0.32 V. The presented biocompatible electrode provides a sustainable alternative to metal-based and critical raw material-based electrodes for bioelectrochemical systems. [ABSTRACT FROM AUTHOR]

Terpenoid is an important group of compounds not only as biocomponents but also as useful secondary metabolites. A volatile terpenoid 1,8-cineole, which is used as a food additive, flavoring agent, cosmetic, etc., is also attracting attention from a medical perspective due to its antiinflammation and antioxidation. The 1,8-cineole fermentation using a recombinant Escherichia coli strain has been reported, although a carbon source supplement is necessary for a high-yield 1,8-cineole production. We constructed the 1,8-cineole-producing cyanobacteria toward a carbon-free and sustainable 1,8-cineole production. cnsA, the 1,8-cineole synthase gene in Streptomyces clavuligerus ATCC 27064, was introduced and overexpressed in the cyanobacterium Synechococcus elongatus PCC 7942. We succeeded in producing an average of 105.6 μg g −1 wet cell weight of 1,8-cineole in S . elongatus 7942 without supplementing any carbon source. Using the cyanobacteria expression system is an efficient approach to producing 1,8-cineole by photosynthesis. [ABSTRACT FROM AUTHOR]

Dimensions of particulate matter found in the water column of marine and freshwater environments (the pelagic realm) range from nanometers to tens of meters. Included in this enormous size range are miniature bacteria, phytoplankton (photosynthetic microalgae), mixoplankton (mixotrophic microorganisms), micro- to meter sized drifting animals (zooplankton), plastic particles, detrital aggregates and fecal pellets, fish, whales and many others. These particles and organisms are involved in many different processes and perform a multitude of services, such as in oceanic biogeochemistry (carbon fixation, oxygen production, carbon export and others) or human nourishment (fisheries). Digital optical tools used in pelagic imaging approaches now allow to bridge this enormous size span and to image micro- to meter-sized objects in situ or on discrete samples. Monitoring plankton, nekton, and particle dynamics at spatial and temporal scales that enable effective management of marine and freshwater environments poses a collective challenge for society. We here argue that a global, distributed and operational network for pelagic imaging is needed and within reach, and we provide recommendations how it can be attained via the voluntary activities of the pelagic imaging community and strategic support from funding agencies and other stakeholders. [ABSTRACT FROM AUTHOR]

Treating wounds with multidrug-resistant bacterial infections remains a huge and arduous challenge. In this work, we prepared a "live-drug"-encapsulated hydrogel dressing for the treatment of multidrug-resistant bacterial infections and full-thickness skin incision repair. Our live dressing was comprised of photosynthetic bacteria (PSB) and extracellular matrix (ECM) gel with photothermal, antibacterial and antioxidant properties, as well as good cytocompatibility and blood compatibility. More interestingly, live PSB could be regarded as not only photothermal agents but also as anti-inflammatory agents to promote wound healing owing to their antioxidant metabolites. In vitro and in vivo studies showed that the PSB hydrogel not only had a high killing rate against methicillin-resistant Staphylococcus aureus (MRSA) but it also accelerated collagen deposition and granulation tissue formation by promoting cell proliferation and migration, which significantly promoted skin tissue regeneration and wound healing. We believe that the large-scale production of PSB Gel-based therapeutic dressings has the advantages of easy use and promising clinical applications. Rapid wound healing and the treatment of bacterial infections have always been the two biggest challenges in the field of wound care. We prepared a "live drug" dressing by encapsulating photosynthetic bacteria into an extracellular matrix hydrogel to sterilize the wound and promote wound healing. First, photosynthetic bacteria are not only a photothermal agent for photothermal wound sterilization, but also possess the anti-inflammatory capacity to enhance wound healing due to their antioxidant metabolites. Second, the extracellular matrix hydrogel is rich in a variety of growth factors and nutrients to promote cell migration and accelerate wound healing. Third, photosynthetic bacteria are not only green and non-toxic, but also can be obtained on a large scale, which facilitates manufacturing and clinical transformation. [Display omitted] [ABSTRACT FROM AUTHOR]

Since the main causative agent for local aggressive periodontitis was the Aggregatibacter actinomycetemcomitans bacteria (A. actinomycetemcomittans). Purple leaves (Graptophyllum pictum (L) Griff.), which contain antibacterial compounds such as flavonoids, tannins, saponins, steroids, and alkaloids, are chosen as one of the natural medicinal ingredients. However, such antibacterial compounds that contain 70% ethanol and 96% ethanol are different. This study proves the differences between the antibacterial effect of 70% and 96% of ethanol extract of purple leaves against the A. actinomycetemcomitans bacteria. This study, purple leaf Simplicia, was extracted with 70% and 96% ethanol using the maceration method. The antibacterial power test has carried out using the serial dilution method to determine MIC and MBC. The diffusion method on the Luria Bertani media utilized to measure the inhibition zone has formed. It has revealed that there was no significant difference between the number of growths of bacterial colonies on MIC and MBC for 70% and 96% ethanol extract of purple leaves. MIC and MBC in 70% and 96% ethanol extract of purple leaves were 3.125% and 6.25%. Unlike the serial dilution test, the diffusion test obtained a significant difference with p=0.019 (p=<0.05). In ethanol, 96% of the inhibition zone's diameter is 13.13 mm, and in 70% ethanol, is 16.5 mm. In short, 70% and 96% ethanol extract of purple leaves has the same antibacterial effect on A. actinomycetemcomittans bacteria. However, the extra antibacterial activity of 70% ethanol in bacteria is more than the 96% ethanol extract of purple leaves. [ABSTRACT FROM AUTHOR]

While the model bacteria Escherichia coli and Bacillus subtilis harbor single chromosomes, which is known as monoploidy, some freshwater cyanobacteria contain multiple chromosome copies per cell throughout their cell cycle, which is known as polyploidy. In the model cyanobacteria Synechococcus elongatus PCC 7942 and Synechocystis sp. PCC 6803, chromosome copy number (ploidy) is regulated in response to growth phase and environmental factors. In S. elongatus 7942, chromosome replication is asynchronous both among cells and chromosomes. Comparative analysis of S. elongatus 7942 and S. sp. 6803 revealed a variety of DNA replication mechanisms. In this review, the current knowledge of ploidy and DNA replication mechanisms in cyanobacteria is summarized together with information on the features common with plant chloroplasts. It is worth noting that the occurrence of polyploidy and its regulation are correlated with certain cyanobacterial lifestyles and are shared between some cyanobacteria and chloroplasts. NGS: next-generation sequencing; Repli-seq: replication sequencing; BrdU: 5-bromo-2′-deoxyuridine; TK: thymidine kinase; GCSI: GC skew index; PET: photosynthetic electron transport; RET: respiration electron transport; Cyt b6f complex: cytochrome b6f complex; PQ: plastoquinone; PC: plastocyanin. Replication cycle of the cyanobacterium Synechococcus elongatus PCC 7942. [ABSTRACT FROM AUTHOR]

Phycosynthesis or algae mediated iron nanoparticle synthesis presents a sustainable, eco-friendly and non-toxic approach to keep up with its expanding applications. Cyanobacteria and algae -the photosynthetic cryptogams with high growth rate, wide range of cell types and simple harvesting procedure, serve as favoured organisms for nano biosynthesis. Generally zerovalent iron nanoparticles along with different oxides with varied morphology like -rod, spherical, spindle and cubes are produced by these bioreagents. Chemically iron oxides like Fe 2 O 3, Fe 3 O 4 and hydroxide FeOOH are produced in nano forms by cyanobacteria, microalgae and seaweeds in an eco-friendly environment. Upon exposure to a precursor solution, the biomolecules present in these organisms act as reducing and capping agents, resulting in nanoiron production. For microscopic unicellular algae, live cell suspension-mediated intracellular synthesis is frequently favoured, and macro algae like seaweeds are used as cell free extract to stimulate extracellular production. More than ten phaeophycean species have been discovered to produce iron nanoparticles in cell free extract conditions. Different genera from different phyla of algae are capable of producing nano iron particles as reported so far. The exposure time and other reaction parameters like pH, temperature, etc. define the physicochemical characteristics of nanoparticles which determine their unique application. Some applications include biomedical technologies, removal of heavy metal contamination, solving agricultural issues catering to the food and energy demand and iron shortage in the human population. This study summarises the results of the last fifteen years of investigation on the phycosynthesis of nanoiron-which expanded significantly over the past five years. • Phycosynthesis is a sustainable eco-friendly approach to synthesize iron nanoparticles. • Synthesis of zerovalent iron nanoparticles, Fe 3 O 4, Fe 2 O 3, and FeOOH have been reported so far. • Different bio active biomolecules in algae act as reducing and capping agents to synthesis Iron nanoparticles. • Iron nanoparticles have wide range of applications including medical and other industrial fields. [ABSTRACT FROM AUTHOR]

Intensive farming practices are typically used for aquaculture. To prevent disease outbreaks, antibiotics are often used to reduce pathogenic bacteria in aquaculture animals. However, the effects of antibiotics on water quality and microbial communities in euryhaline fish culture ponds are largely unknown. The aim of this study was to investigate the interactions between sulfamethoxazole (SMX), water quality and microbial communities in milkfish (Chanos chanos) culture ponds. The results of small-scale milkfish pond experiments indicated that the addition of SMX decreased the abundance of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB) and photosynthetic bacteria. Consequently, the levels of ammonia and total phosphorus in the fish pond water increased, causing algal and cyanobacterial blooms to occur. In contrast, the addition of the SMX-degrading bacterial strains A12 and L effectively degraded SMX and reduced the levels of ammonia and total phosphorus in fish pond water. Furthermore, the abundances of AOB, NOB and photosynthetic bacteria were restored, and algal and cyanobacterial blooms were inhibited. This study demonstrate the influences of SMX on water quality and microbial community composition in milkfish culture ponds. Moreover, the use of the bacterial strains A12 and L as dual function (bioaugmentation and water quality maintenance) beneficial bacteria was shown to provide an effective approach for the bioremediation of SMX-contaminated euryhaline milkfish culture ponds. Image 1 • Beneficial bacteria for bioaugmentation and water quality maintenance. • SMX effects on water quality of milkfish pond were revealed. • SMX effects on microbial compositions of milkfish pond were revealed. • Results of this study provide a strategy for aquaculture water sustainability. This study demonstrate the influences of SMX and SMX-degrading bacteria on the water quality and microbial composition in milkfish culture ponds. [ABSTRACT FROM AUTHOR]

Abstract Plant allelochemicals effectively inhibit and/ or control algal growth, and have potential to use as algaecide. To uncover the lethal mechanism of 2 anti-algal compounds linalool and α-terpineol identified from Cinnamomum camphora extracts, and promote their development as algaecide, the H 2 O 2 production, photosynthetic abilities, caspase-like activities, nuclear changes and DNA degradation were investigated in Chlamydomonas reinhardtii treated with the 2 compounds. H 2 O 2 content burst in linalool treatment at 0.5 h and in α-terpineol treatment at 1 h, with increases of 2.7 folds and 1.3 folds, respectively, compared to that at 0 h. The photosynthetic pigments gradually degraded, and Fv/Fm gradually declined to zero, indicating that the cell death was not a necrosis due to the gradual disappearance of physiological process. In C. reinhardtii cells, the caspase-9-like and caspase-3-like were activated in the treatments with the 2 compounds for 1 h. With prolonging the treatment time, the fluorescent intensity of the cell nucleuses stained by DAPI gradually enhanced and then faded, and the genomic DNA isolated from the cells gradually degraded. These hallmarks indicated that the death of C. reinhardtii cells in linalool and α-terpineol treatments was a programmed cell death (PCD) triggered by the increased reactive oxygen species (ROS). Compared to α-terpineol treatment, linalool treatment showed stronger promoting effects on PCD at the same time point, which may be caused by the higher ROS content inducing higher caspase-9-like and caspase-3-like activities in a short time. Highlights • H 2 O 2 burst in C. reinhardtii treated with linalool at 0.5 h and α-terpineol at 1 h. • Cell death caused by the 2 agents was not necrosis, as the Fv/Fm gradually declined. • Caspase-9-like and caspase-3-like were activated by linalool and α-terpineol. • Nucleuses condensed firstly and then broke, and DNA gradually degraded. • The 2 compounds killed the alga by inducing PCD, and linalool showed stronger effect. [ABSTRACT FROM AUTHOR]

Abstract This study aimed to investigate the possibility to remove mercury (Hg) using the live or dead biomass of Hg resistant purple nonsulfur bacteria (PNSB) for their potential application to clean up shrimp ponds and during cultivation. The efficiency of Hg2+ removal by three PNSB strains; Rhodovulum sulfidophilum SRW1–5, and Afifella marina strains SSS2-1 and SSW15-1, grown with 2 different growth conditions (microaerobic light and aerobic dark conditions) were tested (2 mg/L HgCl 2 , 4.5 mg dry cell weight/mL, 30 min). It was found that the efficiency to remove Hg2+ by the dead cells of all strains was significantly higher than for live cells; and the most effective strain was SSS2-1. The highest Hg2+ removal under the optimum conditions using a 4 mg/L initial HgCl 2 concentration by live and dead cells grown with both incubation conditions were approximately 87% and 95%, respectively. Under both incubation conditions, Hg2+ biosoption by strain SSS2-1 fitted the Freundlich model for live cells and the Langmuir model for dead cells. The kinetics of Hg2+ biosorption by both cell types of strain SSS2-1 suggests the process as a pseudo-second order kinetic model. This study demonstrates that biomass of the strain SSS2-1 has great potential for its biosorption to remove Hg2+ from contaminated areas like shrimp ponds. Highlights • Live cells were less effective to remove Hg2+ than dead cells in all strains tested. • Biomass of Afifella marina strain SSS2-1 was the most effective to remove Hg2+. • Hg2+ biosorption by the strain SSS2-1 fitted the Freundlich model for live cells. • Hg2+ biosorption by the strain SSS2-1 fitted the Langmuir model for dead cells. • Hg2+ biosorption by SSS2-1 (both cell types) was a pseudo-second order kinetic model. [ABSTRACT FROM AUTHOR]

Abstract Herbicides are increasingly recognised as sources of water pollution. Glyphosate-based herbicides (GBHs) are widely used because of their low cost and high effectiveness. By measuring the photosynthetic efficiency of Fucus virsoides fronds exposed to a GBH (Roundup® Power 2.0), we investigated the effect of a continuous exposure (6 days) and the potential of recovery after a short exposure (24 h). Both experiments were carried out combining GBH with and without nutrient enrichment, simulating a runoff event. A factorial experimental design allowed us to assess the potential of interactions between GBH and nutrients, which are likely to co-occur in coastal areas. Our results show deleterious effects of GBH at low concentration on F. virsoides , independently from the duration of exposure and the presence of nutrients. Graphical abstract Image Highlights • We tested the effects of glyphosate-based herbicide (GBH) on Fucus virsoides (Ochrophyta). • The photosynthetic efficiency of Fucus was reduced by 95% after 6 days of exposure to GBH. • Fucus showed irreversible damage even with short time of exposure to GBH (1 day). • The use of herbicides on land might drive the reduction of marine macroalgal communities. • Land-sea planning in ecosystem-based management is a priority. The use of herbicides on land might represent an underestimated threat for coastal systems, as suggested by the irreversible impact on the macroalgae Fucus virsoides observed after a short experimental exposure to a common glyphosate-based herbicide. [ABSTRACT FROM AUTHOR]

Cyanobacteria, alike microalgae, are photosynthetic microorganisms found in different environmental conditions. These photosynthetic bacteria are also considered promising solutions for cracking problem in concretes. These photosynthetic organisms precipitate CaCO 3 crystals in concrete microcracks and pores, thus sealing the cracks and increasing the strength gain of the concrete blocks. Cyanobacteria Lyngbya sp., Phormidium sp., and microalgae Chlorella vulgaris were studied initially. Lyngbya sp., Phormidium sp., and Chlorella vulgaris have the additional property of secreting the exopolysaccharide (EPS). EPSs are an important class of biopolymers with great ecological importance. Because of their high charge density and capacity to act as mineralization nucleation sites, cyanobacterial exopolysaccharides are currently receiving more attention. Using the three strains stated above, this study investigates the impact of physiochemical factors on biomass concentration and exopolysaccharide synthesis and creates mathematical models. Using Central Composite Design (CCD), it is possible to study the interactions between the many parameters, including nitrate concentration, starting media pH, light intensity, and temperature. The biochemical characteristics of the leftover biomass are assessed after exopolysaccharide extraction, and because of its high carbohydrate and fat content, it can be used to produce biofuel. The study of checking the microbial crack healing capacity and strength gain of the concrete using these three cyanobacterial strains is being studied. Based on the outcome, the best species was chosen. Further microstructural analyses, such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to support the calcium carbonate precipitation. [Display omitted] [ABSTRACT FROM AUTHOR]

Developing new modalities that allow multidimensional therapy with optical and immunological regulations is a challenge ahead of pharmacology and drug discovery for effective cancer treatment. To this end, superior purple photosynthetic bacteria, which show unique near-infrared (NIR) fluorescence, strong photothermal conversion ability, and high biocompatibility, were screened from various bacterial strains. To improve the therapeutic performances of screened bacteria, we further designed and developed simple chemical bacterial membrane functionalization with bioactive molecules and polyethylene glycol derivatives. Exploring the physicochemical and physiological properties of the chemically functionalized bacteria complexes achieved excellent tumor targeting and strong anticancer efficacies. The highly biocompatible functional bacteria showed cytotoxic immunological effects, strong NIR fluorescence, and powerful photothermal conversion in the targeted tumor milieu under biologically penetrating NIR light irradiation. [Display omitted] • Purple photosynthetic bacteria were chemically functionalized with bioactive molecules and polyethylene glycol derivatives. • The light-driven functional bacteria showed effective optical and immunological functions in cancer therapy. • The near-infrared fluorescence of bacterial complexes could be used to identify location of tumors for cancer diagnosis. [ABSTRACT FROM AUTHOR]

Free-living Symbiodinium , which forms symbiotic relationships with many marine invertebrates, plays an important role in the vast ocean. Nutrient levels have been shown to significantly impact microbial community structure and regulate algal communities. In this study, the bacterial community structure within the phycosphere of free-living Symbiodinium underwent significant changes in response to nutrient stimulation. Alteromonas exhibited dominance in Zobell 2216E broth nutrient stimulation concomitant with the demise of algal cells. Alteromonas abrolhosensis JY-JZ1, a marine bacterium isolated from the phycosphere of Symbiodinium , demonstrated an algicidal effect on Symbiodinium cells. Optical and scanning electron microscopy revealed that the algal cell membrane structure was disrupted, leading to intracellular leakage. Strain JY-JZ1 exerted its cytotoxicity by producing and secreting bioactive compounds into the supernatant. The marked declines in the chlorophyll a content, photosynthetic efficiency (Fv/Fm) and the electron transport rate (rETR) indicated that the photosynthetic system of Symbiodinium was damaged by JY-JZ1 supernatant. The observed elevation in levels of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) content suggested that the algal cells experienced oxidative stress. Moreover, the supernatant exhibited remarkable adaptability to temperature and pH. Additionally, it displayed exceptional algicidal efficacy against various harmful algae species. To the best of our knowledge, this study represents the first successful isolation of an algicidal bacterial strain from the phycosphere of free-living Symbiodinium and subsequent investigation into its mechanism for controlling Symbiodinium growth, thereby providing novel insights into algae-bacteria interactions. The remarkable algicidal efficacy exhibited by strain JY-JZ1 against other harmful algae species suggests its significant potential for harmful algal blooms (HABs) control. [Display omitted] • Bacterial community structure of phycosphere changed during nutrient stimulation. • Alteromonas became dominant genus accompanied by algal cells death. • A. abrolhosensis JY-JZ1 with algicidal activity was isolated and identified. • Strain JY-JZ1 induced oxidative stress and photosynthetic damage of Symbiodinium. • JY-JZ1 supernatant showed good adaptability and excellent application potential. [ABSTRACT FROM AUTHOR]

Forest management involving the selective logging of exotic species in order to reestablish native flora alters microclimatic conditions and selects for species with heightened capacity to adapt to the new conditions. This study investigated whether, after forest management involving the removal of eucalyptus, ultrastructural adjustments in the chloroplast fostered the photoacclimation of the most abundant regenerating native species in a Brazilian Atlantic forest biological reserve. The influence of seasonality on photosynthetic activity and water use efficiency after the forest management was also assessed. To achieve this, in the rainy season mature leaves of native tree saplings ( Xylopia sericea , Siparuna guianensis , and Byrsonima sericea ) were subjected to ultrastructural analyses and the C isotopic composition (δ 13 C) was determined; and in the dry and rainy season gas exchange and chlorophyll a fluorescence were measured. Species samples were obtained in: secondary forest, a eucalyptus understory with 15 years of regeneration before and 12 months after the management, and from herbarium samples from eucalyptus understories collected at the beginning of forest regeneration (9–16 years ago, for δ 13 C analyses only). Ultrastructural alterations such as the reorganization of thylakoids, starch grain changes, and the presence of plastoglobules and oils were verified after the management in all the species. F v /F m values varied between 0.80 and 0.90 regardless of the management or season of the year. There was a reduction of C assimilation after the management, especially in the dry season. 13 C enrichment was observed for B. sericea , S. guianensis , and X. sericea in herbarium samples (−31.4‰, −32.0‰, and −31.4‰, respectively) and after the forest management (−31.2‰, −32.5‰, −31.4‰), while samples depleted in 13 C were registered before the management (−33.4‰, −33.3‰, −33.2‰) and in the secondary forest (−34.0‰, −33.9‰, and −33.6‰). The data suggest that ultrastructural alterations may have aided in maintaining electron flow after the increase in irradiance due to the forest management, avoiding photochemical stress, as evidenced by F v /F m values. The forest management increased the efficiency of water use and fostered abiotic conditions similar to those present at the beginning of the understory regeneration. These previous conditions favored the current high level of abundance of these three species, highlighting the importance of monitoring to ensure that the management practices do not promote the future dominance of few species at the expense this biome’s high biodiversity. [ABSTRACT FROM AUTHOR]

The livestock wastewater treatment plant represents an important reservoir of antibiotic resistance determinants in the environment. The study explored the prevalence of five antibiotic resistance genes (ARGs, including sul I, tet A, qnr D, mph B and mcr −1) and class 1 integron ( int I1) in a typical livestock wastewater treatment plant, and analyzed their integrated association with two metal resistance genes ( cop A and czc A), two pathogens genes (Staphylococcus and Campylobacter), bacterial community and wastewater properties. Results indicated that all investigated genes were detected in the plant. The treatment plant could not completely remove ARGs abundances, with up to 2.2 × 10 4 ~3.7 × 10 8 copies/L of them remaining in the effluent. Mcr −1 was further enriched by 27-fold in the subsequent pond. The correlation analysis showed that mph B significantly correlateed with tet A and int I. Mcr −1 strongly correlated with cop A. Mph B and int I significantly correlated with czc A. The correlations implied a potential co-selection risk of bacterial resistant to antibiotics and metals. Redundancy analyses indicated that qnr D and mcr −1 strongly correlated with 13 and 14 bacterial genera, respectively. Most ARGs positively correlated to wastewater nutrients, indicating that an efficient reduction of wastewater nutrients would contribute to the antibiotic resistance control. The study will provide useful implications on fates and reductions of ARGs in livestock facilities and receiving environments. [ABSTRACT FROM AUTHOR]

Gram-negative bacterial quorum sensing is mainly regulated by an extracellularly produced N-acylhomoserine lactone (AHL). AHL consists of a lactone ring and an acyl chain, which generally varies from C4 to C18 in length and affords species-specific variety. In this study, we developed an ultra-high performance liquid chromatography tandem mass spectrometry system and detected two kinds of long chain AHLs with chain length C20 from the reverse-phase thin layer chromatography-fractionated cultured supernatant of the marine photosynthetic bacterium Rhodovulum sulfidophilum. By fragmentation search analysis to detect compounds with a homoserine lactone ring moiety for data dependent acquisition, a minor AHL, presumed to be 3-OH-C18-homoserine lactone (HSL), was also found. Among the detected C20-HSLs, 3-OH-C20-HSL was structurally identified and 3-OH-C20:1-HSL was strongly suggested. To our knowledge, this is the first report to show a novel AHL with the longest C20 acyl side chain found to date. Abbreviations: AGC: automatic gain control; AHL: N-acylhomoserine lactone; CD: cyclodextrin; CID: collision induced dissociation; DDA: data dependent acquisition; EPI: enhanced product ion; FISh: fragment ion search; HCD: high energy collisional dissociation; HSL: homoserine lactone; IT: injection time; LC: liquid chromatography; MS: mass spectrometry; PRM: parallel reaction monitoring; RP: reverse phase; SRM: selected reaction monitoring; TLC: thin layer chromatography; UHPLC: ultra high performance liquid chromatography [ABSTRACT FROM AUTHOR]

Highlights • The types of water medium for microalgae cultivation are discussed. • Comparison of different microalgae species for strain selection are analysed. • Cultivation techniques using photobioreactors are elaborated in detail. • The different types of growth modes for microalgae cultivation is evaluated. • Advantages and drawbacks of cultivation modes is explained. Abstract As the world's natural fuel sources continue to deplete, the search for alternative fuel sources intensifies. A promising fuel source alternative is biofuels from microalgae, due to it being a renewable source, its wide availability, and also its high production rate. This paper reviews recent developments in microalgae culture medium, cultivation systems and growth modes. The importance of identifying the type of medium suitable for microalgae cultivation is highlighted along with descriptions and comparison of the medium types that include freshwater, saltwater and wastewater. The different cultivation systems such as open system, closed system, dark system and offshore cultivation used for cultivating microalgae are discussed, along with a study on the impact of large scale cultivation using these systems. Besides that, various growth modes for microalgae cultivation like phototrophic, heterotrophic, mixotrophic, photoheterotophic modes are reviewed. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Immobilized photosynthetic bacteria (PSB) for degrading p-nitroaniline wastewater were prepared with different embedding materials. By comparing several kinds of immobilization process, optimal embedding materials containing diatomite, sodium alginate, polyethylene glycol (PEG), and PVA were obtained. The influence of various operating conditions on the biodegradation of p-nitroaniline was systematically analyzed. Optimization of parameters revealed that the optimal operating conditions of immobilized PSB for degradation of p-nitroaniline wastewater are as follows: light, aerobic, particle size 3-4 mm, embedding ratio 14%, and microsphere dosing quantity 150 g L-1. The degradation rate of immobilized cells was higher than that of free cells. When the concentration of p-nitroaniline is 100 mg L-1, the removal rate was 99.2% by the immobilized cells biodegradation after 3 days. Furthermore, the immobilized bacteria maintained a high degradation rate following storage for 35 days and eight repetitions of the degradation experiment, which shows that immobilized microspheres can be widely used in p-nitroaniline degradation applications. [ABSTRACT FROM AUTHOR]

Growth inhibition ofRhodobacter sphaeroidesf. sp.denitrificansIL106 by nitrite under anaerobic-light conditions became less pronounced when the gene encoding nitrite reductase was deleted. Growth of another deletion mutant of the genes encoding nitric oxide reductase was severely suppressed by nitrite. Our results suggest that nitrite reductase increases the sensitivity to nitrite through the production of nitric oxide. The lack of nitrite reducing ability (nirK) in a denitrifying purple bacterium increased the tolerance to nitrite under anaerobic lighted conditions. [ABSTRACT FROM PUBLISHER]

A gymnodinioid photosynthetic dinoflagellate was isolated from Argentina and examined by light and electron microscopy and analysis of nuclear-encoded LSU rDNA. Kirithra asteri gen. et sp. nov. was proposed as morphology and molecular phylogeny separated this dinoflagellate from others within the family Ceratoperidiniaceae. Cells were surrounded by a hyaline amphiesma comprising polygonal vesicles. Each vesicle contained a honeycomb and a trilaminar structure. An anterior sulcal extension ending in a complete circle formed the apical structure complex (ASC), which characterizes Ceratoperidiniaceae. The ASC comprised three rows of vesicles. The nucleus was located in the hypocone, and several large, irregularly shaped vesicles were present in the epi- and hypocone. Chloroplasts were surrounded by three membranes, and grana-like arrangements of thylakoids were observed in one strain used for ultrastructural study. The cell centre contained 1-3 multiple-stalked pyrenoids and membrane-bound vesicles containing tile-like structures surrounded each pyrenoid. Two pusules with collecting chambers and associated vesicles branched off each of the flagellar canals. The flagellar apparatus featured a ventral connective between the amphiesma and the R1 root, and almost opposite basal bodies, rarely seen in dinoflagellates. This was the first ultrastructural study of a species within Ceratoperidiniaceae. [ABSTRACT FROM AUTHOR]

This study investigated the culturable aerobic phototrophic bacteria present in soil samples collected in the proximity of the Belgian Princess Elisabeth Station in the Sør Rondane Mountains, East Antarctica. Until recently, only oxygenic phototrophic bacteria ( Cyanobacteria ) were well known from Antarctic soils. However, more recent non-cultivation-based studies have demonstrated the presence of anoxygenic phototrophs and, particularly, aerobic anoxygenic phototrophic bacteria in these areas. Approximately 1000 isolates obtained after prolonged incubation under different growth conditions were studied and characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Representative strains were identified by sequence analysis of 16S rRNA genes. More than half of the isolates grouped among known aerobic anoxygenic phototrophic taxa, particularly with Sphingomonadaceae , Methylobacterium and Brevundimonas . In addition, a total of 330 isolates were tested for the presence of key phototrophy genes. While rhodopsin genes were not detected, multiple isolates possessed key genes of the bacteriochlorophyll synthesis pathway. The majority of these potential aerobic anoxygenic phototrophic strains grouped with Alphaproteobacteria ( Sphingomonas , Methylobacterium , Brevundimonas and Polymorphobacter ). [ABSTRACT FROM AUTHOR]

Bioremediation with photosynthetic bacteria (PSB) is thought to be a promising removal method for hexavalent chromium [Cr(VI)]-containing wastewater. In the present study, Rhodobacter sphaeroides (R. sphaeroides) SC01 was used for the investigation of Cr(VI) removal in Cr(VI)-contaminated solution in the presence of melatonin. It was found that exogenous melatonin alleviated oxidative damage to R. sphaeroides SC01, increased Cr (VI) absorption capacity of cell membrane, and improved the reduction efficiency of Cr(VI) via the activation of chromate reductants. The results showed that melatonin could further promote the increase in Cr(VI) removal efficiency, reaching up to 97.8%. Furthermore, melatonin application resulted in 296.9%, 44.4%, and 69.7% upregulation of ascorbic acid (AsA), glutathione (GSH), and cysteine (Cys) relative to non-melatioin treated R. sphaeroides SC01 at 48 h. In addition, the resting cells, cell-free supernatants (CFS), and cell-free extracts (CFE) with melatonin had a higher Cr(VI) removal rate of 18.6%, 82.0%, and 15.2% compared with non-melatonin treated R. sphaeroides SC01. Fourier transform infrared spectroscopy (FTIR) revealed that melatonin increased the binding of Cr(III) with PO43− and C O groups on cell membrane of R. sphaeroides SC01. X-ray diffractometer (XRD) analysis demonstrated that melatonin remarkably bioprecipitated the production of CrPO 4 ·6H 2 O in R. sphaeroides SC01. Hence, these results indicated that melatonin plays the important role in the reduction and uptake of Cr(VI), demonstrating it is a great promising strategy for the management of Cr(VI) contaminated wastewater in photosynthetic bacteria. [Display omitted] • Melatonin alleviated Cr(VI)-induced oxidative damage in Rhodobacter sphaeroides SC01. • Melatonin increased the absorption capacity of R. sphaeroides SC01 to Cr(VI). • Melatonin improved Cr(VI) reduction via non-enzymatic reduction pathways in R. sphaeroides SC01. • Melatonin-mediated Cr(VI) removal mechanism was deduced in R. sphaeroides SC01. [ABSTRACT FROM AUTHOR]

As molybdenum (Mo) is an indispensable metal for plant nitrogen metabolisms, accumulation of dissolved Mo into bacterial cells may connect to the development of bacterial fertilizers that promote plant growth. In order to enhance Mo bioaccumulation, nitrogen removal and light illumination were examined in anoxygenic photosynthetic bacteria (APB) because APB possess Mo nitrogenase whose synthesis is strictly regulated by ammonium ion concentration. In addition, an APB,Rhodopseudomonas palustris, transformed with a gene encoding Mo-responsive transcriptional regulator ModE was constructed. Mo content was most markedly enhanced by the removal of ammonium ion from medium and light illumination while their effects on other metal contents were limited. Increases in contents of trace metals including Mo by the genetic modification were observed. Thus, these results demonstrated an effective way to enrich Mo in the bacterial cells by the culture conditions and genetic modification. Mo content was specifically enhanced in N-deprived photosynthetic bacterium harboring a gene coding Mo-binding protein (FL, full-length; CT, Mo-binding domain; EV, vector). [ABSTRACT FROM PUBLISHER]

The community structure and biomass of pelagic phototrophs, with particular attention to the picoplanktonic size fraction, were studied in a eutrophic Lake Strzeszyñskie in the Wielkopolska Lakeland (western Poland). Phototrophic community included prokaryotic cells, such as oxyphotobacteria (cyanobacteria), anoxyphotobacteria, eukaryotic cells representing cryptophytes, dinophytes, diatoms, chrysophytes, xanthophytes, haptophytes, and green algae. 112 taxa of the phototrophs were recorded. Most of them were eukaryotic cells (83 species), including chlorophytes (48) and diatoms (15). The range of the photortophs biomass was between 0.1 and about 3 mg l-1, and its maximum was at 8 m depth, mostly due to eukaryotic cells. In the shallower waters layers the contributions of the cyanobacteria and the eukaryotes to the total biomass were very similar. Starting from 10 m anoxyphotobacteria increased in importance and near the bottom their contribution to phototrophic biomass exceed 50%. The smallest phototrophs were dominated by the picocyanobacteria. The joint contribution of pico- and nanoplankton in the water column ranged significantly. In the epilimnion it was about 30%, in the upper part of metalimnion it reached 50%, and in the lower part of hypolimnion they accounted for 70% of total phototrophic biomass. In the microplankton, the highest biomass was produced by the filamentous cyanobacteria and phytoflagellates. These examinations are pointing out to the need for a holistic approach to the photosynthetic organisms and show that at increasing depths different groups of phototrophs play the role as major producers. [ABSTRACT FROM AUTHOR]

To promote hydrogen production of immobilized photosynthetic bacteria, an annular fiber-illuminating bioreactor (AFIBR) for biofilm formation on the surface of side-glowing optical fiber was developed. Mathematical model on coupled mass transport processes of substrate transport and biodegradation within biofilm with substrate diffusion and convection within bulk flow region during continuous hydrogen production was proposed. Effects of mass transfer on performance of substrate bio-degradation were investigated. 10 g/L inlet substrate concentration and 100 mL/h flow rate were identified to be Optimum conditions for maximal substrate degradation in the bioreator. [ABSTRACT FROM AUTHOR]

The goal of this study was to explain the influence of the total porosity and the surface roughness on the susceptibility of clay bricks to biodegradation by phototrophic microorganisms. In addition, this correlation was studied on both specimens treated with TiO 2 nanocoating and untreated control specimens. The effect of UV intensity on the photocatalytic power of T i O 2 was also investigated. An accelerated fouling test was performed by sprinkling a suspension of Chlorella mirabilis and Chroococcidiopsis fissurarum on sample surfaces. These two test strains were chosen because their representativeness on building clay brick façades subjected to biofouling. The gradual superficial accumulation of algal biomass on treated and control specimens was evaluated by means of image analysis and colour measurement. Two specimens' parameters, namely porosity and roughness, were examined. Results showed that both the specimen microstructure and roughness of the surface play a key role in the colonization of clay bricks because they were able to provide more nutrient to the algal cells anchored to the surface. The T i O 2 nanocoating was able to inhibit the biofouling of clay bricks irradiated with UV-A light, except in the case of high porous rough specimens. [ABSTRACT FROM AUTHOR]

In this study, we used a photosynthetic bacteria as a host to construct a novel engineered bacterium Rhodopseudomonas palustris expressed with the metallothionein (MT) from the freshwater crab (Sinopotamon honanense), and to investigate its removal and biosorption capacity for Cd, Zn and Cu in medium and the possible mechanism(s). The results showed that: (i) the MT expressed recombinant was constructed successfully; (ii) the order of heavy metal sensitivity of the recombinant was Cd > Cu > Zn, and the maximum biosorption capacities calculated by Langmuir model were 224.22, 233.64 and 99.8 mg/g, respectively. Compared to the wild-type, the recombinant has doubled biosorption capacity to Cd and Cu with higher sorption rates and was less influenced by different culturing factors (time, metal concentration and pH), which allowed it rapid removal of 92.1% of 25 mg/L Cd within 30 mins; (iii) the recombinant exhibited more diverse biosorption patterns, and the proportion of its intracellular uptake was significantly (P < 0.05) increased 10% under different conditions; (iv) the functional groups on the cell membrane of the recombinant involved in the metal biosorption were more selective, and the synthesis of metal nanoparticles might be reused as optoelectronic materials for recycling. Based on the findings, we concluded that under various culturing conditions, the recombinant can remove the metals examined more successfully and efficiently. Therefore, as a novel strain, the recombinant has great potential for application in the removal and recovery of metals from wastewater or other polluted water sources. [Display omitted] • Recombinant R. palustris had stronger Cd2+, Zn2+ and Cu2+ biosorption capacity. • Biosorption capacity of recombinant R. palustris was less affected by environmental factors. • Changes of cell surface binding, elements and functional groups were demonstrated by FTIR, SEM and EDS. • Recombinant R. palustris had the potential to form various nanometallic particles. [ABSTRACT FROM AUTHOR]

Wastewater, as the used water, carries huge energy that is frequently ignored and unexploited. Microbes, as bioelectrocatalysts in microbial electrochemical systems (MESs), can convert chemical energy stored in biodegradable matrixes from wastewater to bioelectricity and chemicals. However, due to sluggish wastewater treatment rates and bioenergy production, wider applications have been hampered. Currently, photo-assisted MESs, combined electrochemical/photochemical driving force with microbial catalysis, have emerged as a sustainable platform to enhance pollutants degradation and bioenergy recovery from wastewater with the aid of solar light, accompanied by reasonable energy investment and minimal environmental disturbance. Nevertheless, the development of photo-assisted MESs is still in its infancy. This work broadly concludes present photo-assisted MESs wastewater treatment technologies and their overall limitations in terms of performance and the future advancements that will be necessary to make them more widely applicable. Herein, crucial factors influencing the performance of these photo-assisted MESs, such as the reactor types (bioanode-photocathode, photoanode-biocathode, photomicrobial electrode, and photosynthetic bacteria/algae MESs), the bandgap of semiconductor and microbe species are discussed. Furthermore, prominent research accomplishments of photo-assisted MESs with an emphasis on eliminating contaminants (initial concentration, removal efficiency, and removal rate) and recovering bioenergy (product types, production rate, and current density) from various wastewaters are systematically summarized. Finally, present challenges and prospects in the field of photo-assisted MESs technology are discussed, mainly including the optimization of electrode materials, screening and culture of microorganisms, scale-up of bioreactors, intermittency of solar energy, and other complications overarchingly shared with photo-assisted microbial electrochemical wastewater treatment and bioenergy recovery. Graphical Abstract [Display omitted] [ABSTRACT FROM AUTHOR]

The article offers information on a study related to removal of radioactivity from soil in Fukushima-ken, Japan. It informs about the removal of radioactivity from polluted soil in Fukushima-ken was done using a photosynthetic bacterium, rhodobacter spliaeroides SSI, immobilized in alginate beads by aerobic treatments.

The article cites a research study that describes the removal of radioactivity from sediment mud in a swimming pool by immobilized photosynthetic bacteria. The alginate immobilized photosynthetic bacterium Rhodobcater sphaeroides SSI was used to remove about 90% of the radioactive Cs in the sediment mud of a school's swimming pool in Fukushima, Japan.

GJ-22, a strain of the photosynthetic bacterium (PSB) capable of degrading cypermethrin (CPM), was isolated from the sludge from the wastewater treatment unit of an insecticide factory. The strain showed relatively high CPM degradation ability and was identified as Rhodopseudomonas palustris on the basis of its culture characteristics, co-lony and cell morphology, living cell absorption spectrum analysis, physiological and biochemical characteristics, type of internal photosynthetic membrane, and 16S rRNA sequence phylogenetic analysis. Single-factor tests showed that CPM degradation by GJ-22 was good from 25°C to 35°C, but that the optimal temperature was 30°C; a pH of 7.0 was optimal for both initial growth and CPM degradation. GJ-22 completely transformed CPM at a concentration of 50 mg/L at 30°C, pH 7.0, and 7,500 lux within 7 days. Under optimal conditions, within a week, GJ-22 degraded 83.5% of CPM, 77.1% of fenpropathrin, 71.2% of bifenthrin, and 31.1% of ethofenprox at concentrations of 100 mg/L. The metabolic products were detected by per-forming gas chromatography/mass spectrometry (GC/MS) analysis; the analysis showed that GJ-22 oxidation or/and hydrolysis degraded CPM, yielding 5 metabolites. [ABSTRACT FROM AUTHOR]

To improve the wastewater treatment efficiency and enhance the resource recovery efficiency, this paper studied the effects of trace elements, Fe, Mn, Cu, Zn, Co, Mg, on photosynthetic bacteria (PSB) growth in wastewater. Two most prominent factors that influence the biomass of PSB were identified through single element design. Optimal concentrations of these trace elements were found through the Box-Behnken design and the response surface analysis. The results showed that the best situation was as follows: 0.66 mmol · L-1 Fe2+ and 0.16 mmol · L-1 Mg2+, the maximum biomass of PSB reached 1 483.5 mg/L, the maximum COD removal ratio was 89.1%, and the additional cost was RMB 0. 033 Yuan/t. The confirmatory tests showed that the combination of Fe and Mg achieved a PSB biomass of 1 380 mg · L-1 after 72 h, which was 57% higher than the control. Fe and Mg could promote PSB growth in wastewater and enhance the resource recovery efficiency. [ABSTRACT FROM AUTHOR]

Iron availability has long been known to impact the growth of cyanobacteria in both freshwater and marine aquatic environments. Iron is a key element in a number of critical cellular components, including the photosynthetic light-harvesting complexes and nitrogenases, and thus regulation of iron availability is central to optimal growth and productivity in phototrophic and diazotrophic cyanobacteria. Most reported studies investigating cyanobacterial responses to iron stress have focused on the impact of iron availability on growth rates and related physiological processes. Specific physiological effects observed for cyanobacterial cells grown under iron-limited conditions include the regulation of pigmentation and morphology. Characterized molecular responses of cyanobacteria to iron limitation include the induction of iron-scavenging systems as well as the substitution of iron-independent cofactors to maintain intracellular iron homeostasis and preserve vital physiological processes. The focus of this report is an examination of recent findings on the impact of iron limitation on the growth and development of the freshwater filamentous cyanobacterium Fremyella diplosiphon. This filamentous cyanobacterium has served as a model for studies on the photoregulation of photosynthetic efficiency that is a core part of the light-dependent acclimation response known as complementary chromatic adaptation. Recent studies in F. diplosiphon identified photoregulated genes that were implicated to have roles in iron-related processes. Based on these findings, an investigation into the relationship between light and iron levels on growth and development in F. diplosiphon was initiated. Studies on the impact of iron limitation on the growth, cellular development, and specific functional roles of some of the molecular players involved in the organismal response to iron deficiency were conducted. Acclimation responses to iron-limited growth conditions by F. diplosiphon, and cyanobacteria more generally, are discussed here. [ABSTRACT FROM AUTHOR]

This paper studied the physiological and biochemical characteristics of a new strain of photosynthetic bacteria isolated from soil in details, identified its belonging, and used it to treat artificial soybean wastewater and reclaim resources. Results showed that the strain belonged to Rhodopseudomonas sphaeroides, and was named Z08. For treating wastewater with COD of 8 000 - 12 000 mg · L-1 under 26 - 28 °C, the optimal dose of PSB was 160 - 400 mg · L-1; COD removal reached 85% after 72 h. Various oxygen - light conditions were examined, and the best one was found to be natural light - micro oxygen condition. Under this condition, COD removal reached 73.5% and biomass reached 2 125 mg · L-1 after 72 h treatment. The optimal condition of Z08 treating soybean wastewater was as follows: natural light and micro oxygen condition, Z08 dose of 160 - 400 mg · L-1, and hydraulic retention time of 72 h. [ABSTRACT FROM AUTHOR]

To test biomass of photosynthetic bacteria ( PSB ) in water, and to provide a way of PSB sewage reclamation, this paper adopted HPLC to analyze the concentration of CoQ10 and thus obtained the concentration of PSB in water. The results show that the chromatographic condition is as follows: The chromatographic column is SphherisorbC18 ( 10 cm x 4.6 mm ID) ; methanol-absolute alcohol (9:1) as mobile phase at a flow rate of 1 mL/min; column temperature 35 °C ; Wave Length of UV detector 275 nm; sample size 15 µL; column pressure 16.4 MPa. By extracting 5 h with acetone, volatilizing acetone completely and dissolving it with absolute alcohol, this method may obtain the maximum relative extraction of CoQ10. The average recovery ratio of external reference method is 99.13% and RSD 0. 81%. The highest radiance-extraction is acetone extraction 5 h before evaporating completely and then solving in ethanol. The concentration of CoQ10 in PSB in various cultural conditions and growing phases is quite stable. The impurities or microbes in wastewater do not affect the testing result. The concentration of PSB is (Y + 37.487)/25.431 g · L-1, Y is peak area (V · s). This method is simple and accurate, and can be used for quantitative analysis of PSB in water. [ABSTRACT FROM AUTHOR]

The article presents a study that deals with the association between the photosynthetic endosymbionts and scleractinian corals inhabiting deep reef ecological systems. It assesses the deep-water Symbiodinium diversity from 10 different coral genera at a depth range of 45 to 70 meters on the Great Barrier Reef in Australia. It employs denaturing ingredient gel electrophoresis fingerprinting of the internal transcribed spacer region of the ribosomal DNA to establish Symbiodinium identity. It stresses the need to examine symbiont diversity across broad environmental ranges.

Abstract: At the Nakabusa hot spring, Japan, dense olive-green microbial mats develop in regions where the slightly alkaline, sulfidic effluent has cooled to 65°C. The microbial community of such mats was analyzed by focusing on the diversity, as well as the in situ distribution and function of bacteria involved in sulfur cycling. Analyses of 16S rRNA and functional genes (aprA, pufM) suggested the importance of three thermophilic bacterial groups: aerobic chemolithotrophic sulfide-oxidizing species of the genus Sulfurihydrogenibium (Aquificae), anaerobic sulfate-reducing species of the genera Thermodesulfobacterium/Thermodesulfatator, and filamentous anoxygenic photosynthetic species of the genus Chloroflexus. A new oligonucleotide probe specific for Sulfurihydrogenibium was designed and optimized for catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH). In situ hybridizations of thin mat sections showed a heterogeneous vertical distribution of Sulfurihydrogenibium and Chloroflexus. Sulfurihydrogenibium dominated near the mat surface (50% of the total mat biovolume), while Chloroflexus dominated in deeper layers (up to 64% of the total mat biovolume). Physiological experiments monitoring in vitro changes of sulfide concentration indicated slight sulfide production by sulfate-reducing bacteria under anoxic-dark conditions, sulfide consumption by photosynthetic bacteria under anoxic-light conditions and strong sulfide oxidation by chemolithotrophic members of Aquificae under oxic-dark condition. We therefore propose that Sulfurihydrogenibium spp. act as highly efficient scavengers of oxygen from the spring water, thus creating a favorable, anoxic environment for Chloroflexus and Thermodesulfobacterium/Thermodesulfatator in deeper layers. [Copyright &y& Elsevier]

Abstract: In order to bridge the gap between the crystal structure of photosynthetic pigment-protein complexes and the data gathered in optical experiments, two essential problems need to be solved. On one hand, theories of optical spectra and excitation energy transfer have to be developed that take into account the pigment-pigment (excitonic) and the pigment-protein (exciton-vibrational) coupling on an equal footing. On the other hand, the parameters entering these theories need to be calculated from the structural data. Good agreement between simulations and experimental data then allows to draw conclusions on structure-function relationships of these complexes and to make predictions. In the development of theory, a delicate question is how to describe the interplay between the quantum dynamics of excitons and the dephasing of coherences by the coupling of excitons to protein vibrations. Quantum mechanic coherences are utilized for efficient light harvesting. In the reaction centers of purple bacteria an energy sink is created by a coherent coupling of exciton states to intermolecular charge transfer states. The dephasing of coherences can be monitored, e.g., by the temperature dependent shift of optical lines. In the Fenna-Matthews-Olson protein, which acts as an excitation energy wire between the outer chlorosome antenna and the reaction center complex, an energy funnel for efficient light-harvesting is formed by the pigment-protein coupling. The protein shifts the local transition energies of the pigments, the so-called site energies in a specific way, such that pigments facing the reaction center are redshifted with respect to those on the chlorosome side. In the light-harvesting complex of higher plants an excitation energy funnel is created by the use of two different types of chlorophyll (Chl) pigments, Chla and Chlb and by the pigment-protein coupling that creates an energy sink at Chla 610 located in the stromal layer at the periphery of the complex. The close contact between Chla and Chlb gives rise to ultrafast subpicosecond exciton transfer, whereas dynamic localization effects are inferred to lead to long ps relaxation times between the majority of Chla pigments. [Copyright &y& Elsevier]

Polar organic chemical integrative samplers (POCIS) are valuable tools in passive sampling methods for monitoring polar organic pesticides in freshwaters. Pesticides extracted from the environment using such methods can be used to toxicity tests. This study evaluated the acute effects of POCIS extracts on natural phototrophic biofilm communities. Our results demonstrate an effect of POCIS pesticide mixtures on chlorophyll a fluorescence, photosynthetic efficiency and community structure. Nevertheless, the range of biofilm responses differs according to origin of the biofilms tested, revealing spatial variations in the sensitivity of natural communities in the studied stream. Combining passive sampler extracts with community-level toxicity tests offers promising perspectives for ecological risk assessment. [Copyright &y& Elsevier]

Plastids are found across the tree of life in a tremendous diversity of life forms. Surprisingly they are not limited to photosynthetic organisms but also found in numerous predators and parasites. An important reason for the pervasiveness of plastids has been their ability to move laterally and to jump from one branch of the tree of life to the next through secondary endosymbiosis. Eukaryotic algae have entered endosymbiotic relationships with other eukaryotes on multiple independent occasions. The descendants of these endosymbiotic events now carry complex plastids, organelles that are bound by three or even four membranes. As in all endosymbiotic organelles most of the symbiont''s genes have been transferred to the host and their protein products have to be imported into the organelle. As four membranes might suggest, this is a complex process. The emerging mechanisms display a series of translocons that mirror the divergent ancestry of the membranes they cross. This review is written from the viewpoint of a parasite biologist and seeks to provide a brief overview of plastid evolution in particular for readers not already familiar with plant and algal biology and then focuses on recent molecular discoveries using genetically tractable Apicomplexa and diatoms. [Copyright &y& Elsevier]

Mixotrophy is the occurrence of phagotrophy and phototrophy in the same organism. In ciliates the intracellular phototroph can be unicellular green algae (zoochlorellae), dinoflagellates (zooxanthellae), cryptomonads or sequestered chloroplasts from ingested algae. An intermediate mixotrophic mechanism is that where the phagotroph ingests algal cells, maintains them intact and functional in the cytoplasm for some time, but the algae are afterwards digested. This seems to occur in some species of Mesodinium. Ciliates with phototrophic endosymbionts have evolved independently in marine and freshwater habitats. The enslaved algal cells or chloroplasts provide host cells with organic matter. Mixotrophs flourish in oxygen–rich, but also in micro–aerobic waters and in the complete absence of oxygen. In the latter case, the aerobic host retains aerobic metabolism, sustained by the oxygen produced by the phototrophic endosymbionts or the sequestered chloroplasts. Mixotrophic ciliates can attain spectacular abundances in some habitats, and entirely dominate the ciliate community. [ABSTRACT FROM AUTHOR]

This paper discusses the possibility and optimal conditions of brewery wastewater treatment using a new strain of photosynthetic bacteria (Z08). Light-anaerobic, natural light-microaerobic, and dark-aerobic operational conditions were explored to treat the wastewater and recover bacterial protein. The results show that the COD removal ratio under light-anaerobic condition (88%) is greater than that under natural light-mi- croaerobic condition (74%), ant it is also greater than that under dark-aerobic condition (62%) ; total bacterial growth ratio under light-anaerobic condition (38%) is greater than that under natural light-microaerobic condition ( -35% ), and it is also greater than that under dark-aerobic condition ( -43% ) ; hydraulic retention time under light-anaerobic condition (240 h) is longer than that under natural light-microaerobic condition (60 h) and that under dark-aerobic condition (36 h). It is feasible to use Z08 to treat beer wastewater and recover bacteria cell mass. The recommended conditions are as follows: anaerobic in daytime and aerobic at night, with additional artificial light when needed. Under such conditions, pollutants in the wastewater can be rapidly transformed into bacterial cell mass for utilization with a transformation efficiency of 26% for single cell protein. [ABSTRACT FROM AUTHOR]

Abstract: Four species of marine purple sulfur bacteria of the genus Marichromatium have been validly described. A recent re-analysis of the 16S rRNA-based similarity and genomic DNA–DNA hybridizations (DDH) of the type strains suggested that some of them are so closely related that they can be considered heterotypic synonyms. Here, we report on the evaluation of the multilocus sequence analysis approach (MLSA) for nine Marichromatium strains in order to resolve their intrageneric genealogical relationships. MLSA was based on six protein-coding genes (gyrB, recA, fusA, dnaK, pufM, and soxB), and the results were comparable to DDH. The phylogenetic tree constructed with the concatenated sequences, which also included the 16S rRNA gene and the internal transcriber spacer ITS region (4331bp), separated the nine strains in four lineages that reflected the four Marichromatium species. The reconstructed phylogenetic tree based on concatenation of six protein-coding genes was also highly congruent with the tree topology based on the 16S rRNA gene. [Copyright &y& Elsevier]

Abstract: Hydrogen is a clean energy alternative to fossil fuels. Photosynthetic bacteria produce hydrogen from organic compounds under anaerobic, nitrogen-limiting conditions through a light-dependent electron transfer process. In this study, the hydrogen production efficiency of phototrophic bacteria, Rhodobacter capsulatus and its Hup mutant strain (an uptake hydrogenase deleted strain) were tested on different initial acetate concentrations at fluctuating temperatures with indoor and outdoor photobioreactors. Acetate was effectively metabolized and H2 was produced at a high rate. Increasing the initial acetate concentration resulted in a shift in the utilization kinetics of acetate from first order to second order. The effects of fluctuating temperature and day/night cycles on hydrogen production were also studied in indoor and outdoor conditions using acetate as the carbon source. Temperature fluctuations and day/night cycles significantly decreased hydrogen production. It was found that the Hup mutant strain of R. capsulatus has better hydrogen productivity than the wild type parent in outdoor conditions. [Copyright &y& Elsevier]

The article presents a study which examines the role of malic enzyme (ME) in the metabolic regulation of Rhodopseudomonas palustris a purple nonsulfur bacterium. It says that ME is believed to generate pyruvate and is associated with gluceogenesis. It cites the methods used in the study such as purification of ME, electrophoresis, and molecular weight estimation. Results showed that ME catalyzed the anaplerotic reaction of the bacterium and has a feedback regulation mechanism.

Abstract: The phototrophic communities in meromictic, perennially ice-covered Lake A, on Ellesmere Island in the Canadian High Arctic, were characterized by pigment analysis using high performance liquid chromatography. Samples were taken to determine the vertical changes down the water column as well as a variation between years. These analyses showed that Lake A had distinct phototrophic communities in its oxic and anoxic layers. The pigment analyses indicated that phototrophic biomass in the upper, oxic waters was dominated by picocyanobacteria, while in the lower, anoxic layer photosynthetic green sulphur bacteria were dominant. Interannual variation in pigment concentrations was related to the penetration of photosynthetically active radiation in the water column, suggesting that light availability may be limiting the net accumulation of photosynthetic bacterial biomass in Lake A. Pigment analysis of the surface sediments indicated that deposition was dominated by the photosynthetic sulphur bacterial contribution. The sedimentary record of bacterial pigments in polar meromictic lakes offers a promising tool for the reconstruction of past changes in ice cover and therefore in climate. [Copyright &y& Elsevier]